PAID JOB FOR USB C to CIGARETTE ADAPTER

Community Jobs and Paid Consultancy
1

I am after two of these. I am not an electrician and I had someone help me put this scope together.

[PAID] Fan‑less, palm‑sized USB‑C → 12 V @ 8 A (≈ 100 W) adapter

What I need

A silent, enclosed cigarette‑lighter socket powered from a 20 V × 5 A USB‑C PD port, able to deliver 12 V at up to 8 A continuously.

Project summary

  • Vehicle USB‑C outlet already supplies the full 100 W PDO (20 V × 5 A).
  • Goal: run a ~90 W device plus other 12 V accessories where no factory socket exists.

Key constraints

  • Absolutely no fan and no audible coil‑whine.
  • Finished look: one USB‑C lead in, one flush‑mounted cigarette‑lighter outlet out.
  • OEM‑style faceplate for behind‑seat / foot‑well mounting.

Preferred parts (or equivalent)

  1. USB‑C PD trigger ≥ 5 A, preset 20 V – e.g. DAOKI PD2/3 trigger (ASIN B091GGVS9Z).
  2. Sealed DC‑DC buck 9‑36 V → 12 V ≥ 10 A, ≥ 90 % eff. – e.g. XWST 12 V 10‑15 A (ASIN B0CZLC7847).
  3. Panel‑mount female cigarette‑lighter socket ≥ 15 A with cap.
  4. 0.5 – 1 m e‑marked USB‑C cable, 5 A/100 W.
  5. Enclosure – choose one:
    • Hammond 1455C801 aluminium (80 × 54 × 23 mm) – converter bonded to wall as heatsink, or
    • Custom 3‑D‑printed PETG/ABS shell (deck‑of‑cards size) with standoffs and strain‑relief.
  6. Inline mini‑blade fuse holder + 10 A fuse on 12 V.

Mechanical / wiring notes

  • Ship with PD trigger already set to 20 V.
  • Keep 12 V wiring < 10 cm; 16 AWG silicone.
  • Bond converter thermally to enclosure; case must stay < 55 °C at 8 A.
  • Provide cable gland / moulded strain relief on USB‑C lead.
  • Case colour: black or dark grey; de‑burr all openings.

Bench‑test acceptance

Test Pass criteria
Continuous load 11.9 – 12.1 V @ 8 A for 30 min
Ripple < 50 mV p‑p
Inrush ≥ 12 A for 100 ms, no drop below 11.5 V
Noise No fan, no audible whine
Thermals Case exterior < 55 °C

Deliverables

  • Fully assembled, tested unit.
  • Internal photos before final close‑up.
  • Short test report (scope capture of ripple + temp reading).
  • Shipping to Melbourne, Australia.

Please quote

  • Parts + labour cost (AUD or USD).
  • Lead‑time.
  • Any substitution suggestions or questions.

Thanks for reading – happy to discuss details here or by DM.

2

Why don't you buy one, e.g. form aliexpress?

Well, anyway, what's your budget?

3

I cannot find one that exists that can carry that amount of sustained power. We are talking sustained 95w+ - nothing on the market that I can see can do that.

I have no idea on what to expect for budget but I am open within reason.

4

Get a 12V lead-acid battery + low speed charging circuit + 12V stepdown. That will cost you ~ 100 bucks and will work. If you think custom design is cheaper ... check the other threads, you'll find nice numbers given.

5

Thanks but I am after what I posted above.

6

My guess: Nobody will answer till you give your budget. Anyway, good luck with it.

7

Here's a 100W one on Amazon.
Look at this product I found on google.com HATMINI 100W PD3.1 USB C to Car Cigarette Lighter Adapter Cable

I can build you a few if you want. Main concern would be the efficiency: if the vehicle can only supply 100W, then getting 90W out may not be feasible. In any case, a custom designed unit will be well into 4 figures. Are you sure your application can support that?

8

I don't think that one will do 100W at 12V; USB-C (v1) only gets up to 100W when providing 20V (5A max, regardless of voltage.)
So OP needs a 20V USB negotiation. followed by a (highly efficient) 20V to 12V step-down converter. It sounds ... difficult.

An interesting project, and I'd like to applaud OP's detailed description of requirements - it was a lot better than the usual "I want someone to build me an X" requests that usually show up here.

If only you had USB2-C v3.x supply (up to 240W at 48V, but still 5A), DC-DC converters with 48V input are quite common. (Hmm. But about the same price as those with 20V inputs, if purchased new. high power 3.3 and 5V modules frequently show up on the surplus market.)

93% efficient (seems about the best there is): MYBEA01210CZTB Murata Power Solutions Inc. | Power Supplies - Board Mount | DigiKey
(No, I don't think that any custom design is going to do much better than 93% efficiency. ~7W power dissipation at 100W - a fanless design might get pretty toasty!)